(i) Field of the Invention
The present invention relates to a novel photosensitive heat-resistant polymer and a method for preparing the same. More specifically, it relates to a novel high-sensitivity photosensitive poly(amide)imide precursor having an excellent shelf stability, a method for preparing the same, a photosensitive polymer composition containing the same, and a method for forming a patterned poly(amide)imide film by the use of the same.
(ii) Description of the Related Art
Photosensitive polyimides which are heat-resistant photosensitive materials have been widely used as insulating films and passivation films for semiconductors, but these polyimides have various problems.
For example, Japanese Patent Application Laid-open No. 54-145794 suggests a method for mixing a compound containing a double bond and an amino group or its quaternary salt with a polyamic acid, but the change in the viscosity of the resultant solution inconveniently increases with time, since the compound containing a large amount of the amino group or its quaternary salt is added to the unstable polyamic acid solution. Japanese Patent Application Laid-open Nos. 55-45746 and 60-100143 suggest methods for reacting an unsaturated epoxy compound or an isocyanate compound having a double bond with the carboxyl group of various polyamic acids. However, when the photosensitive unsaturated group-containing compound is reacted with the carboxyl group of the polyamic acid, a part of the polyamic acid, for example, decomposes, so that the viscosity of the solution changes inconveniently. In Japanese Patent Application Publication No. 55-41422, there is suggested a polymer obtained by introducing an active functional group such as a double bond into the ester side chain of the polyamic acid, but when an acid chloride is reacted with a diamine, the chloride remains as an impurity, and the removal of this impurity is troublesome. Furthermore, Japanese Patent Application Laid-open No. 60-6729 suggests that a diamine having a double bond is previously synthesized and a polyimide is then synthesized by using the diamine, but a process for introducing the photosensitive functional group is intricate and a large cost is required.
As is apparent from the foregoing, conventional techniques have various problems, and it is desired to develop a photosensitive material by which the above-mentioned problems can be solved.